The MongoGridFS class

(PECL mongo >=0.9.0)

Introduction

Utilities for storing and retrieving files from the database.

GridFS is a storage specification all supported drivers implement.
Basically, it defines two collections: files, for file
metadata, and chunks, for file content. If the file is
large, it will automatically be split into smaller chunks and each chunk
will be saved as a document in the chunks collection.

Each document in the files collection contains the filename, upload date,
and md5 hash. It also contains a unique _id field, which
can be used to query the chunks collection for the file's content. Each
document in the chunks collection contains a chunk of binary data, a
files_id field that matches its file's
_id, and the position of this chunk in the overall file.

Of course, the default chunk size is thousands of bytes, but that makes an unwieldy example.

Inter-Language Compatibility

You should be able to use any files created by MongoGridFS with any other
drivers, and vice versa. However, some drivers expect that all metadata
associated with a file be in a "metadata" field. If you're going to be
using other languages, it's a good idea to wrap info you might want them to
see in a "metadata" field. For example, instead of:

The MongoGridFS Family

MongoGridFS represents the files and chunks
collections. MongoGridFS extends MongoCollection,
and an instance of MongoGridFS has access to all of
MongoCollection methods, which act on the files
collection:

There are some methods for MongoGridFS with the same
name as MongoCollection methods, that behave
slightly differently. For example, MongoGridFS::remove()
will remove any objects that match the criteria from the files collection
and their content from the chunks collection.

To store something new in GridFS, there are a couple options. If you have
a filename, you can say:

Querying a MongoGridFS collection returns a
MongoGridFSCursor, which behaves like a normal
MongoCursor except that it returns
MongoGridFSFiles instead of associative arrays.

MongoGridFSFiles can be written back to disc using
MongoGridFSFile::write() or retrieved in memory using
MongoGridFSFile::getBytes(). There is currently no
method that automatically streams chunks, but it would be fairly easy to
write by querying the $grid->chunks collection.

MongoGridFSFile objects contain a field file which
contains any file metadata.